Do any of you guys use neoprene foam for
insulation?

I bought some rolls of this stuff cheap on ebay. Stuck down to the bottom and side panel of the case. It seems to cut down on quite a bit of the subtle vibration that I can hear when my hearing is super sensitive as I'm falling asleep (I listen to internet radio type stuff to help me sleep).

Only problem is, this stuff was crappy and is starting to lift off. The adhesive was excellent, but neoprene itself lifted off the adhesive, but the adhesive was itself stuck fast to the surface.